Cat 426 Fuel Tank Cleanout/Repair

Hello all. Well i finally got around to addressing my dirty fuel tank on my Cat 426 Backhoe SN SBC00580. It has been a thorn in my side since it bought it as it would go thru a fuel filter in no time at all. So i installed a "pre" fuel filter that was before the (lift) fuel pump to help keep the new pump free of debris. My intention all along was to pull the tank and clean it and install a new pickup tube because it runs out of fuel when there is still over 1/4 tank fuel left. That told me the pickup tube had holes in it. So with some spare time on my hands today i pulled the tank.
It was not all that hard. There are 4 hydraulic line mounts that have to come loose plus the fuel line out and the return line. Then there are four bolts that hold the tank to the frame. When I drained the tank i could see all kinds of rust, sand and just foreign objects that had no business being in the tank. Initially when i loosened the drain plug and removed it nothing came out BC the crud was deep and plugged the drain. A long screwdriver fixed that tho.
I have attached a couple of pics that show the key points of this operation. One is the holes in the frame where the tank attaches to, one is the supply line that attaches to the tank and one identifies the terminal where the pickup tube is located. You can also see t2 of the hydraulic lines mounting surface.

Now here is what i need help on. I thought that once i removed the supply line connector from the tank i could just reach in and remove the pickup tube. But after several attempts to get that tube out i concluded that it must be welded in place? So has anyone else found this to be true or do i need to just work harder at getting it out? My search of the internet and in the parts manual finds on reference to a pickup tube. I then searched Cat Parts listing and came up empty handed as well.
If this tube is permanently affixed to the mounting block you see in the pics, how does one get a replacement.?

The pickup tube is part of the fuel tank. If you buy a pickup tube the tank is free
According to the parts catalog you 9R-5139.

If it was me I would take the tank to a welding/Fab shop and have them cut the tank open, blast the crud out of it, weld in a new tube and weld it back up. I like fixing stuff the right way.

If you want to try the DIY, cheap route you can buy a universal type pickup tube and fit it to the tank and come up with a way to fit it to the fuel line. They make them for boat fuel tanks.

At the very least make sure to clean the tank. You can put some nuts or rocks in the tank and shake it. It is heavy so might be tough to do. Start it to a trailer and take a ride down a bumpy road. You can also use some rust converter to stop the rust. Keeping it filled with clean fuel will also stop the rust. One of the reasons there is a fuel tank drain is to drain any water out.

You other option is to hunt down a used one.

edgephoto said:

The pickup tube is part of the fuel tank. If you buy a pickup tube the tank is free
According to the parts catalog you 9R-5139.

If it was me I would take the tank to a welding/Fab shop and have them cut the tank open, blast the crud out of it, weld in a new tube and weld it back up. I like fixing stuff the right way.

If you want to try the DIY, cheap route you can buy a universal type pickup tube and fit it to the tank and come up with a way to fit it to the fuel line. They make them for boat fuel tanks.

At the very least make sure to clean the tank. You can put some nuts or rocks in the tank and shake it. It is heavy so might be tough to do. Start it to a trailer and take a ride down a bumpy road. You can also use some rust converter to stop the rust. Keeping it filled with clean fuel will also stop the rust. One of the reasons there is a fuel tank drain is to drain any water out.

You other option is to hunt down a used one.

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LOL. I never suspected that they would make a tank with a permanent pickup tube. Crazy! Somebody must have had stock in a tank mfg company.
Yes, the purpose of taking the tank off was to rectify the dirty tank issues and the pickup tube issue. It will be done right when i am finished. I was going to buy some large ball bearings and put them in the tank and attach the tank to my disc that i have on my other tractor and drive it around "roughly" for a day or two and then clean it out.
As to the pickup tube, i can just drill the old one out to make room for a new one. The new one i will put a slight flare on it and braze onto the connector, 8L-6557, and go from there. When i was a kid the way they cleaned bad fuel tanks was to build a big fire and set the tank on the pile of burning wood. Once it cooled down they would flush it out with water and let it dry, paint it and install. BC that was all they had back in the 40's and 50's.
That is not what i will do. As to what is available here in my city? I can say nothing here that would even come close to being able to work on/fix that tank. I will have to do it all myself.
I was also thinking about cutting that mounting block off and welding the new pickup tube to it and then reweld the block back in place. But that would just take too long and i will go the other route described above.

why waste money on ball bearings? Just grab some nuts and bolts from
the junk jar. Toss them in and do your trick.

If you can drill out the old one and fit a new one, go for it. There is no pressure there so braze will be fine.

Remember, manufacturers do not build things to be easily repairable, they build them to be cost effective to assemble. Something like a fuel tank rarely, if ever, has a defect that would require replacement under warranty.

Fill it with gravel, 1/3 full of water, strap it to the tractor rim while you're disking or anything.

I was thinking grind the welds and pry that block off, then replace and reweld. But if you can drill out the pickup, then tap it for a pipe bushing, that sounds like a good idea.

If it were mine I would clean it with a couple of gallons of full strength muratic acid.
Eye protection and a respirator is mandatory.
Followed with a thorough flush of hot water.
I have done this and the result was quite satisfactory.

Tinkerer said:

If it were mine I would clean it with a couple of gallons of full strength muratic acid.
Eye protection and a respirator is mandatory.
Followed with a thorough flush of hot water.
I have done this and the result was quite satisfactory.

Click to expand...

I like this idea better than mine. How does that acid react when it hits the diesel? I know what it does to bare rust, it eats it up.

Use Dawn Platinum dish-washing detergent to remove the remnants of the fuel.
No need to be real fussy to get all the mixture out before dumping in the acid.

Gas tank sealer probably a good idea then?

Tenwheeler said:

Gas tank sealer probably a good idea then?

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You know, i was just thinking about that!! I read about a sealer a long time ago when i used to rebuild the old Ford tractors. I can't remember the name of the stuff and i never used it BC when i heard about it I also heard it was difficult to apply. So i never thought it was worth the effort. But all those old tanks were gasoline and did not rust up the way these diesel tanks do.
I am leaning toward doing that on this tank BC i plan to keep this hoe for a long time.
Do you know a name product you can recommend?

My friend did his Triumph TR3 about 20 years ago and I did my Jag's fuel tank about 12 years ago. Followed the instructions to the letter. Worked like a charm and did not peel.

https://www.hirschauto.com/ALCOHOL-RESISTANT-GAS-TANK-SEALER/productinfo/GTS/

In my friend's TR3 he used the repair putty to fix some holes. In my case the old Jag had the fuel tank in the trunk and it smelled like gasoline. I found the bottom of the tank had a couple tiny pinholes. The sealer worked as advertised.

There are plenty of brands out there that all claim to be the best. I was happy with the Hirsch stuff. The key to these sealers is to get the tank clean.

I wanted to conclude this thread with the steps i took to clean out that nasty tank and the results.
First off the tank was a mess, rusty bottom and bad pickup problems. Here is some of the stuff that i washed out of it:
A look inside before i disassembled it:
Here is the process, i cut the mounting block off with my handy side grinder with the ultra thin blade. This is 4.5 inch blade.
Notice that the tank is full of soapy water to prevent a fire/explosion.
After i pull it this is what you see, that is tiny pinholes in the pickup tube real close to the mounting block. This tube is made of thick gauge metal and rust resistant. BUT, it did rust through.
The site will not upload more pics so the rest are in the next post.

The extent of that rust damage is quite amazing.
Thanks for posting the photos and information. It will defiantly help others that are having fuel delivery problems to their injector pumps.

Here is how i installed the "new" tube. I drilled out the block to the same diameter as the tube and then forced the tube in and seated before i welded it in place. I used my wire welder instead of brazing because the braze may melt with i weld the block back in place.

Please note the "slots" cut into the end of the tube. The reason for this is the inability to pump fuel if something was sucked up to the open end. I was having issues before where the engine would just stop running BC it was running out of fuel. I would reprime it and it would start up and run for a while and then die again. So my guess it was a combination of the tube clogging up plus that pinhole which was above the fuel level.
Here is tank after sand blasting and painting.

Some other points of interest. I used lots of muriatic acid to clean the tank. It took several washings to get all the sand and rust out. I let the tank sit over 2 days and dry out. Once it was dry i used high pressure air to blow all the fine dust and other debris out. Then i rigged up my small wet or dry vac up with a long small diameter heater hose and vacuumed every square inch of the tank to make sure nothing was left.
Here is a pic of the block off the tank with tube still attached.

Hopefully this story will give all those who own a 426/428 etc that has this fuel tank configuration will give some insight into what the tank has inside. When designing the new tube for installation i made sure it barely touched the bottom before i welded it in place. I am not the best welder so i kind of made a mess but i made sure it did not leak. So pretty does not apply here, just function.

edgephoto said:

My friend did his Triumph TR3 about 20 years ago and I did my Jag's fuel tank about 12 years ago. Followed the instructions to the letter. Worked like a charm and did not peel.

https://www.hirschauto.com/ALCOHOL-RESISTANT-GAS-TANK-SEALER/productinfo/GTS/

In my friend's TR3 he used the repair putty to fix some holes. In my case the old Jag had the fuel tank in the trunk and it smelled like gasoline. I found the bottom of the tank had a couple tiny pinholes. The sealer worked as advertised.

There are plenty of brands out there that all claim to be the best. I was happy with the Hirsch stuff. The key to these sealers is to get the tank clean.

Click to expand...

As you can see i finished that tank over the weekend. I did not opt to use a sealer BC of all the ones i read about, including yours, it said that all metal must be shiny and cleaned of all debris or the sealer would not stick. So there was no way i could ever do that and i figured this tank lasted over 3 decades and it will probably do that much more.
The tip was appreciated.
I sure hope this pans out and all those starting and dying problems are solved. After all, what is left? I have completely rebuilt the entire fue system, that tank was the last item to be done. If this doesn't do it, i am gonna scrap the thing. LOL

The only thing left I can think of is the condition of the steel lines from the tank to the lift pump and any others.

Tinkerer said:

The only thing left I can think of is the condition of the steel lines from the tank to the lift pump and any others.

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The lines from the lift pump and the rubber line on the return line near the lift pump to the tank were "wired out" while i had the tank off. I inspected the outside very carefully and found no rusted spots or holes. I then filled them with brake cleaner capped them off and let set 2 days and then high pressured them out with air. All rubber lines are new and all other steel lines were cleaned when i overhauled the engine last month. Should be good to go. I will know by tomorrow as i am finishing up today and will start engine early tomorrow.

I took mine to a radiator shop. $100 and it looked new inside. I had to cut the filler neck off mine to get it out. I didn't want to pull the motor to get it out. I used a auto fuel tank filler hose and two hose clamps to install it.

Also the filler neck is most likely solder on.

Several people have said to put nut bolts and other things in the tank to aid with cleaning. I just had to clean one just like that tank. Would you guys still suggest putting something in it with the pickup tube in it. I didn’t have to remove the tube so I just used a pressure washer to clean with. Afraid if I put anything in there it might damage the tube.

Clinton Justice said:

Several people have said to put nut bolts and other things in the tank to aid with cleaning. I just had to clean one just like that tank. Would you guys still suggest putting something in it with the pickup tube in it. I didn’t have to remove the tube so I just used a pressure washer to clean with. Afraid if I put anything in there it might damage the tube.

Click to expand...

I have pressure washed several with great results. Depends on what is in the tank I thank.